Planetary Nebula

A planetary nebula is a spectacular glowing shell of ionized gas surrounding the hot, exposed core of a dying star—despite its misleading name, it has nothing to do with planets! When low to medium-mass stars (0.8 to 8 solar masses) exhaust their nuclear fuel, they shed their outer layers in beautiful, expanding gaseous envelopes that glow brilliantly as ultraviolet radiation from the central white dwarf candidate ionizes the expelled material.</p><p>The term "planetary nebula" was coined by astronomer William Herschel in 1785, who thought these circular, disk-like objects resembled planets through his telescope. These cosmic gems typically span 1-5 light-years across and shine for about 10,000 years before fading. Famous examples include the Ring Nebula (M57) in Lyra, resembling a cosmic donut 2,300 light-years away, and the stunning Helix Nebula (NGC 7293)—nicknamed the "Eye of God"—stretching 2.5 light-years across.</p><p>Planetary nebulae serve as crucial laboratories for studying stellar evolution and chemical enrichment of the galaxy. They distribute heavy elements like carbon, nitrogen, and oxygen—forged in stellar cores—throughout space, providing raw materials for future star and planet formation. Our own Sun will likely create such a nebula in about 5 billion years, offering a glimpse into our solar system's distant future.